Wiper with integrated seal

ABSTRACT

A wiper having an integrated seal, comprising at least one dynamically stressed, first sealing lip arranged in the direction of a space to be sealed, and at least one wiping lip disposed on the side facing away from the space to be sealed. The wiper having an integrated seal also includes quasi-statically stressed second, third and fourth sealing lips which are each configured to be placed against at least one counter-surface of a mounting space of the wiper with integrated seal. The second sealing lip is fluid-conductive. The third and fourth sealing lips are each configured as a pressure relief valve, and sealing lips are arranged in series.

FIELD OF THE INVENTION

The present invention relates to a wiper. More specifically, the presentinvention relates to a wiper having an integrated seal.

BACKGROUND INFORMATION

German Patent Application No. 296 16 242 U1 describes a double wiper.The double wiper is provided for sealing a movable part with respect toa pressure system, the double wiper surrounding the movable part as aring. A connection is produced between the two end faces of the doublewiper when an opening pressure in the pressure system is exceeded.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, the presentinvention seeks to provide a wiper of the type described above in such away that the wiper with the integrated seal is relieved from pressure.In addition, the present invention seeks to provide a wiper of the typedescribed above in such a way that penetration of dirt and moisturealong quasi-static sealing lips in the direction of the space to besealed is reliably avoided.

To achieve the objective, a wiper having an integrated seal is provided,including at least one first, dynamically stressed sealing lip arrangedin the direction of the space to be sealed and at least one wiping liparranged on the side facing away from the space to be sealed. Inaddition, the wiper with integrated seal includes three quasi-staticallystressed second, third and fourth sealing lips, which are each able tobe placed against at least one counter-surface of the mounting space ofthe wiper with integrated seal. The second sealing lip isfluid-conductive. Each of the third and fourth sealing lips are formedand operate as a pressure relief valve. The second, third and fourthsealing lips are arranged to function in series. Due to the arrangementof the quasi-statically stressed sealing lips in series, theyessentially function as a labyrinth seal to effectively preventpenetration of impurities from the surroundings past thequasi-statically stressed sealing lips into the space to be sealed.

To avoid an undesirably large displacement of the wiper with integratedseal within its mounting space, the second sealing lip isfluid-conductive, the third and fourth sealing lips are configured as apressure relief valve. The third and fourth sealing lips are able to belifted off of their respective counter-surfaces, for example, inresponse to an opening pressure of approximately 4 bar. The wiper isthereby prevented from being undesirably greatly deformed and/or beingforced out of its mounting space. The third sealing lip is disposedfunctionally between the second and the fourth sealing lips. The thirdsealing lip prevents impurities from the surroundings from being able topenetrate past the second sealing lip into the space to be sealed. Evenif the impurities have already passed the fourth sealing lip, there isno disadvantageous effect on the working properties of the wiper.Because the impurities are reliably held back by the fourth and thirdsealing lips, the second sealing lip does not come into contact with theimpurities. The second sealing lip is thereby protected from wear andtear during a long service life, and dirt is effectively prevented frompenetrating into the space to be sealed off.

Under normal operating conditions, the space to be sealed off in frontof the seal integrated into the wiper is at zero pressure. The space maybe empty, partially filled or completely filled with a medium to besealed off. Under certain conditions, the medium may also be under a lowpressure of up to 4 bar.

The third and fourth sealing lips sealingly abut against the wall of ahousing, the wall bounding the mounting space.

The third sealing lip is configured such that medium to be sealed isreliably held back on the side of the second sealing lip facing thespace to be sealed. A passage of fluid past the third sealing lip in thedirection of the fourth sealing lip is prevented provided that theaforementioned pressure is not exceeded.

The second sealing lip is constructed so that it also abuts against thewall of the housing. However, due to the structure of its surface or dueto small gaps in the sealing edge, the second sealing lip allows a smallvolumetric flow to pass which is sufficient to relieve the pressure.

If the pressure within the space to be sealed rises above 4 bar, forexample, due to leakage of a further seal upstream of the wiper withintegrated seal in the direction of the space to be sealed off, then avolumetric flow takes place past the second sealing lip in the directionof the third sealing lip. Due to the pressure, the third sealing lipallows the volumetric flow to pass in the direction of the fourthsealing lip. The fourth sealing lip lifts off briefly from itscounter-surface, so that the volumetric flow emerges visibly as leakagein the direction of the surroundings. The visible leakage is anindication that seals within the space to be sealed and/or the rod to besealed are damaged/worn out and should be replaced.

Of the quasi-statically stressed sealing lips, at least the secondsealing lip facing the space to be sealed has a surface structure with aroughness R_(a) of greater than 2 μm. Such a surface structure can beachieved, for example, when manufacturing the wiper with integrated sealby forming in a mold having a corresponding surface roughness. Thesurface roughness in the mold can be produced, for example, by erodingthe relevant surface.

It is also possible to produce the surface structure in a differentmanner, for example, by blasting the surface with a granular material ofsteel, non-ferrous metals, sand, ceramics or plastic having a particlesize of the granular material of approximately 2 to 20 μm. The surfaceroughness yields for the medium to be sealed a fluid-conductiveconnection in the direction of the third sealing lip via the secondsealing lip without the second sealing lip lifting off from thecounter-surface. Thus, the surface structure permits a fluid-conductiveconnection between the space to be sealed and the third sealing lip.

The fluid-conductive connection may also be produced or supported by oneor more gaps, for example, by grooves running in the axial direction inthe area of the second sealing edge.

The third sealing lip, arranged between the second and the fourthsealing lips, preferably has a sealing edge which is bounded by twomutually intersecting conical surfaces. The first conical surface facesthe space to be sealed, forming a smaller angle relative to an imaginaryaxis parallel to the axis of symmetry than the second conical surfacefacing away from the space to be sealed. The first conical surfacepreferably forms a first angle of approximately 15° relative to theaxis. The second conical surface preferably forms a second angle ofapproximately 45° relative to the axis.

The third sealing edge may be smooth or else may be provided with astructure similar to the second sealing edge. Due to the comparativelyflat first angle and the steeper second angle, when the opening pressureis exceeded, the third sealing lip is deformed in such a way that themedium to be sealed passes the third sealing lip in the direction of thefourth sealing lip. Advantageously, a volumetric flow is able to travelpast the third sealing lip in the direction of the fourth sealing lip,for example, through grooves extending essentially in the radialdirection, within the sealing ring between the third and the fourthsealing edge, or through channels within the mounting space which arealso not closable by an adjacent seal.

According to a preferred embodiment, the passage may be formed by aplurality of grooves, extending in the radial direction and distributeduniformly in the circumferential direction, which form a component ofthe wiper with integrated seal.

To achieve good seal tightness, the dynamically stressed, first sealinglip preferably has a sealing edge which is sharp or provided with asmall radius of 0.2 mm or less. The wiping lip is preferably rounded,having a radius R=0.2. In contrast, sharp-edged wiping lips wipe off toostrongly, causing unwanted wiper leakage, and, for example, the mediumto be sealed located on a rod is not completely conveyed back again inthe direction of the space to be sealed.

According to a preferred embodiment, the wiper with integrated seal isused in conjunction with one or more upstream rod seals, for example, inbuilding machinery or other applications of mobile hydraulics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cross-sectional view of a wiper having anintegrated seal, according to one embodiment of the present invention;

FIG. 2 is a top view of the wiper having an integrated seal, shown fromthe wiper side and directed toward the surroundings, according to theembodiment of the present invention illustrated in FIG. 1; and

FIG. 3 illustrates the wiper having an integrated seal as shown in FIGS.1 and 2, in the installed state in conjunction with an upstream rodseal.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a wiper having an integrated seal. The wiper withintegrated seal has dynamically stressed, first sealing lip (2) radiallyon the inside, and a likewise dynamically stressed wiping lip (3) on theside facing away from space (1) to be sealed. First sealing lip (2) hasa sharp sealing edge, while wiping lip (3) has a radius of 0.2 mm.Wiping lip (3) is formed in such a way that, when the rod is extended,the wiping lip allows the very thin film of medium to be sealed, whichis located on rod (16) and which is not completely wiped off by firstsealing lip (2), to pass in the direction of the surroundings. When rod(16) is retracted, wiping lip (3) allows this lubricant film to passagain in the direction of space (1) to be sealed, while impurities fromthe surroundings are wiped from the surface of the retracting rod. Thethin film of medium to be sealed located on rod (16) lubricates wipinglip (3).

Radially on the outside, the wiper with integrated seal has three,quasi-statically stressed sealing lips (4, 5, 6) arranged in series.Second sealing lip (4), facing space (1) to be sealed, preferably has asurface structure with a roughness Ra of greater than 2 μm. Thestructure may be produced during manufacturing in a shaping mold havinga corresponding surface roughness. Alternatively, the roughness may beproduced in the mold by an eroding process.

Third sealing lip (5), arranged in the axial direction between secondsealing lip (4) and fourth sealing lip (6), is bounded by the twomutually intersecting conical surfaces (11, 12). First conical surface(11) forms a first angle of approximately 15° relative to a line runningparallel to axis (13) and touching third sealing lip (5), while secondconical surface (12) forms a second angle of approximately 45° relativeto this line.

In this embodiment of the present invention, three grooves (14) areprovided to permit a passage of medium to be sealed past third sealinglip (5) in the direction of fourth sealing lip (6). The three grooves(14) are advantageously distributed uniformly in the circumferentialdirection, which extend essentially in the radial direction. A passageof fluid from third sealing lip (5) in the direction of fourth sealinglip (6) is also possible when the wiper with integrated seal abuts,within its mounting space (8), by way of its areas bordering the grooves(14).

FIG. 3 illustrates the wiper with integrated seal of FIGS. 1 and 2 inthe installed state. A further seal (15) is disposed on the side of thewiper with integrated seal facing space (1) to be sealed.

Only when seal (15) and/or the surface of rod (16) to be sealed exhibitswear and/or damage is medium to be sealed conveyed past seal (15) in thedirection of the claimed wiper with integrated seal and surroundings(9). To avoid an undesirably high pressure build-up between seal (15)and the wiper with integrated seal, the surface of the second sealinglip (4) is provided with a rough, fluid-conducting structure, and thirdsealing lip (5) is able to be lifted from its counter-surface (7), inthe same way as fourth sealing lip (6). A costly pressure-relief borehole in housing (17) is thereby rendered unnecessary.

What is claimed is:
 1. A wiper having an integrated seal, comprising: atleast one dynamically-stressed, first sealing lip arranged in thedirection of space to be sealed; at least one wiping lip disposed on theside facing away from the space to be sealed; and second, third andfourth sealing lips which are three quasi-statically stressed and whichare each configured to be placed against at least one counter-surface ofa mounting space, the second sealing lip being fluid-conductive, thethird and fourth sealing lips each being configured as a pressure reliefvalve, the second, third and fourth sealing lips being arranged inseries.
 2. The wiper as recited in claim 1, wherein of the second, thirdand fourth sealing lips, at least the second sealing lip, facing thespace to be sealed, has a surface roughness R_(a) of greater than 2 μm.3. The wiper as recited in claim 1, wherein the second sealing lip has asmooth surface with a roughness of less than or equal to 2 μm, and thesealing edge has at least one gap in the form of a groove running in theaxial direction.
 4. The wiper as recited in claim 1, wherein the fourthsealing lip, facing surroundings, is further configured to be lifted offof a corresponding counter-surface if a pressure in the space to besealed exceeds a predetermined maximum pressure.
 5. The wiper as recitedin claim 1, wherein the third sealing lip is arranged between the secondsealing lip and the fourth sealing lip, the third sealing lip having asealing edge which is bounded by two mutually intersecting conicalsurfaces, and wherein a first conical surface facing the space to besealed forms a smaller angle relative to an axis parallel to an axis ofsymmetry than a second conical surface facing away from the space to besealed.
 6. The wiper as recited in claim 5, wherein the first conicalsurface forms a first angle of 15° relative to the axis that is parallelto the axis of symmetry.
 7. The wiper as recited in claim 5, wherein thesecond conical surface forms a second angle of 45° relative to the axisthat is parallel to the axis of symmetry.